The present invention relates to an eyeglass lens grinding apparatus for grinding an eyeglass lens so that it conforms to the shape of an eyeglass frame.
An eyeglass lens grinding apparatus is known that grinds the periphery of a rotating lens as it is pressed into contact with an abrasive wheel rotating at a high speed. In grinding the eyeglass lens, it is necessary to use an abrasive wheel suitable for the material of the lens to be processed, and it is also necessary to change the abrasive wheel depending on a specific processing stage such as rough grinding or finish grinding.
Most of the conventional standard arrangements of abrasive wheels have heretofore consisted of three abrasive wheels, i.e. a rough abrasive wheel for use on plastic lenses, a rough abrasive wheel for use on glass lenses and a finishing abrasive wheel. However, with the recent popularity of two-point frames and NYROL (nylon string rolled) frames, a growing demand has arisen for polishing (specular processing) in which a plane-processed lens edge is further polished to produce a mirror-like finish. In some countries, the standard arrangement of three abrasive wheels is sufficient but in other countries a special polishing abrasive wheel is required to provide a mirror-like finish in all edge portions of a lens including a bevelled part.
In order to meet these requirements, one may provide an arrangement of all abrasive wheels that are necessary to accomplish the desired processing operations. However, if all necessary abrasive wheels are made available, the total thickness of the wheels becomes so great that a substantial alteration in mechanism is required but this is impossible to realize with the existing apparatus.
Under the circumstances, manufacturers of lens grinding apparatus have had various types of machines available for different needs, such as one having the standard three-wheel arrangement, one having a four-wheel array including an additional abrasive wheel for polished-plane processing, and one dedicated to the processing of plastic lenses with a three-wheel arrangement capable of rough grinding, finishing and polishing. At the same time, the manufacturers have made available dedicated process control programs that are suited to the respective wheel arrangements.
However, the process control programs are often changed in order to improve the precision of lens processing operations or shorten the processing time. The change of process control programs has to be made for each wheel arrangement, requiring cumbersome program management.
In the process of manufacturing lens grinding apparatus, managing at plurality of software programs for different wheel arrangements is complicated and error-prone. In addition, changing abrasive wheels has not been easy on the part of operators of the apparatus.